Part of fixing graphical rendering bugs: https://github.com/iceiix/steven/issues/25
Corrupted graphics on AMD video cards: https://github.com/Thinkofname/steven/issues/74
The previous workaround set NUM_SAMPLES to 2, but this added an extra texel fetch. Setting to 1 reproduces the 16px blue striped unexpected behavior. Setting to 0 samples avoids the extra fetch and the striping.
This is allowed per http://docs.gl/gl3/glTexImage2DMultisample:
> samples specifies the number of samples in the image and must be in the range zero to GL_MAX_SAMPLES - 1.
iceiix